physics mcq help needed! urgent!

[zxcvbnm]

GPE(initailly)+KE(initail)=GPE(finallt)+work done afgainst friction+KE(final)
50+5=0+10+KE(final)
KE(final)=45

ok thanx but the final g.p.e shouldnt be zero, should it? the object is still at a height...and 50 is the loss in g.p.e, no?
also, please explain june 03, q 20 and 22

[vanibharutham]

dsin(theta)=n(lambda)

d = slit width
theta = angle of the diffraction
n = diffraction order , whether it is 1st maxima, 2nd maxima etc
lambda = wavelength
you use the formula for single slit diffraction

ii) lambda= ax/D
lambda = wavelength
a  = distance between slits/ appertures
x = fringe separation
D = distance of slits from screen/eye/ receiver
this formula is used when you deal with Young's Double Slits and the double slit interference fringes - they form a regular pattern of maxima's...regular FRINGES is what they are called


also what is the forumla of finding work done from a graph of F vs extension, (is it area under graph???)
Yes, area under graph

And what is the unit of Young's modulus....
Pascals or N/m²

Also how do we know from a graph whether a material is ductile, plastic elastic etc etc
Ductile = the graph has a large plastic deformation region
elastic = straight line in the Hooke's Law Region... anything after that it is plastic
Toughness = the greater the area under a curve the tougher the material
Brittle = straight line and no plastic deformation, just a sudden SNAP
any others?

[halosh92]

Can anyone solve and explain the following questions to me please --- (all are in october/november 2008 paper 1 cie physics)
10,11,27,30
Also can someone explain the following formulas --->
i)dsin(theta)=n(lambda)
ii) lambda= ax/D
also what is the forumla of finding work done from a graph of F vs extension, (is it area under graph???)
And what is the unit of Young's modulus....
Also how do we know from a graph whether a material is ductile, plastic elastic etc etc

Q11)
T=tension
A=acceleration
m=mass

T-6=8a
2*9.8 -T=2a

therefore (solve simultaneously)

13.6=10a
1.36=a
nearest to answer A

[samin6n]

O/N 2004 Q 15 ..Please explain!!

[astarmathsandphysics]

GPE is relative. I can say GPE is zero relative to the initial position where it was +50
2003 jun
20 if child can ;lower pressure by 10% there is a net pressure 0.1P_0 =dgh wehere d=density so h=p_0/dg
22 1 spring removed so extension is 3x/2 now weight is doubled so extension is doubled to 3x

[halosh92]

Can anyone solve and explain the following questions to me please --- (all are in october/november 2008 paper 1 cie physics)
10,11,27,30
Also can someone explain the following formulas --->
i)dsin(theta)=n(lambda)
ii) lambda= ax/D
also what is the forumla of finding work done from a graph of F vs extension, (is it area under graph???)
And what is the unit of Young's modulus....
Also how do we know from a graph whether a material is ductile, plastic elastic etc etc

Q27) as its microwaves then its electromagnetic wave..so speed= 3*10^8
v= f lamda
lambda:
from one antinode to the next is 15mm  but thats half a wavelength so one full wavelngth is 30mm
now apply the equation:

(3*10^8)/([15*2]/1000)
 make sure to change mm to m by dividing by 1000 .
answer is C

[halosh92]

Q27) as its microwaves then its electromagnetic wave..so speed= 3*10^8
v= f lamda
lambda:
from one antinode to the next is 15mm  but thats half a wavelength so one full wavelngth is 30mm
now apply the equation:

(3*10^8)/([15*2]/1000)
 make sure to change mm to m by dividing by 1000 .
answer is C

Q30) E=V/d

also  E=F/q
equate:
V/d=F/q
we have to find "q"
so:
660/(15/1000)=F/(4.8*10^-19)
dont forget to change the 15mm to m thats why we divide by 1000
and simply cross multiply.

[halosh92]

O/N 2004 Q 15 ..Please explain!!

ok c :
ke= 1/2mv^2
lets ignore the "m" for now
so we could make use of values here
lets take ke=2
solving:
 2=1/2mv^2
sqrt4= 2=v
therefore     v=2

if it increase by factor of 4 that means:
2*4=8
ke=1/2mV^2
8=1/2mV^2
sqrt16=4=V
V=4

then  V/v = 4/2 = 2
 

[superduper2009]

Q11)
T=tension
A=acceleration
m=mass

T-6=8a
2*9.8 -T=2a

therefore (solve simultaneously)

13.6=10a
1.36=a
nearest to answer A

Thanks alot...
By the way what are the formulas that u used for getting the equations???

[zxcvbnm]

GPE is relative. I can say GPE is zero relative to the initial position where it was +50
2003 jun
20 if child can ;lower pressure by 10% there is a net pressure 0.1P_0 =dgh wehere d=density so h=p_0/dg
22 1 spring removed so extension is 3x/2 now weight is doubled so extension is doubled to 3x

ohh i see...thanx alot!

[halosh92]

Thanks alot...
By the way what are the formulas that u used for getting the equations???

F=ma

ure welcome

[superduper2009]

Thanks SOOOOOOOOO MUCH TO ALL OF U GUYS...
one more doubt :S....
in the case of
dsin(theta) = n(lambda)
how do we calculate d when 1 meter has 1000 gratings is it simply (1/1000)?

[halosh92]

Thanks SOOOOOOOOO MUCH TO ALL OF U GUYS...
one more doubt :S....
in the case of
dsin(theta) = n(lambda)
how do we calculate d when 1 meter has 1000 gratings is it simply (1/1000)?

could u like post the exact question for that?
i think so thats the way u do it ..unless there are some other typical questions.

[superduper2009]

no exact questions.....just wanted to clear a doubt.... thanks so much
and best of luck 4 ur exam

[halosh92]

thx superduper u2

doubt:
june 2006 Q9